Arithmetic Reasoning - General Questions

In a farm there are hens and cows. If the heads number 21 and the legs number 52, how many hens are there?

A teacher has 178 chocolates. If she gives 12 chocolates to each student, she is 2 short. How many students are there?

29 poles are fixed in a straight line, 8 m apart. What is the distance between the first and the last pole?

28 poles are fixed in a straight line, 6 m apart. What is the distance between the first and the last pole?

A teacher has 153 chocolates. If she gives 6 chocolates to each student, she is 9 short. How many students are there?